Cattle grids are often used to prevent livestock, such as sheep, cattle, pigs, horses, or mules, from passing along a road, walkway, cart path, or railway which interrupts fencing surrounding an enclosed border. A typical cattle grid consists of a depression in the road covered by a transverse grid of metal bars or tubes having fixed ends on both sides of the depression, such that the gaps between the bars are wide enough for animals' legs to fall through, but sufficiently narrow to allow a wheeled vehicle or human foot. This provides an effective barrier to animals without impeding wheeled vehicles, as the animals are reluctant to walk on the grates.
Cattle grids, however, are impractical for use with rivers, creeks, streams, canals, ravines, gullies, washes and the like, whether flowing or dry (collectively referred to herein as waterways). Waterways thus present unique challenges as an unwanted path for livestock egress from an otherwise confined land area.
Prior art livestock fences spanning waterways typically involve a support structure mounted on the waterway bed, with a flexible mesh fence extending above the support. However, these fences tend to collect debris, particularly after heavy rains. Accumulated debris poses a risk of upstream flooding, thus requiring regular maintenance.
Other prior art livestock fences spanning waterways involve a horizontal rod, pole, or cable above the bed which supports a hinged fence, vertically hanging chains, or other structure which permits the free flow of water, yet swings out of the way to allow debris to pass underneath the swinging structure. These approaches involve fences that include moving parts, involve regular maintenance, and/or typically require two or more people to install.
A culvert is a structure that allows water to flow under a road, railroad, trail, or similar obstruction from one side to the other side. Typically embedded so as to be surrounded by soil, a culvert may be made from a pipe, reinforced concrete or other material. Culverts are commonly used both as cross-drains for ditch relief and to pass water under a road at natural drainage and stream crossings. A culvert may be a bridge-like structure designed to allow vehicle or pedestrian traffic to cross over the waterway while allowing adequate passage for the water. Presently known culvert designs include rectangular or rounded bars extending parallel to the direction of water flow, supported by supporting members transversely oriented to the direction of flow. These cross members also tend to collect debris, resulting in upstream flooding during heavy rains.
Systems and methods are thus needed which overcome these limitations. Various desirable features and characteristics will also become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background section.